This disclosure relates generally to the surface infiltration of liquids into produce, specifically whole fresh fruits and vegetables. Fresh produce as used herein shall refer to any intact, whole fruit or vegetable product, whether freshly picked or taken from storage without processing such as freezing, or canning. It is directed to pressure penetration using vacuum pressure techniques. It offers an alternative to prior systems in which fruits and vegetables have been pressure treated while immersed in a liquid tank.
The present system was developed specifically in relation to calcium treatments to enhance the firmess qualities of fresh apples. Infiltration of the porous skins of apples by calcium chloride solutions has been found to improve firmness of the fruit through storage and also controls a common aging phenomenon known as "bitter pit". Treated apples have also been found to be less susceptible to bruising.
While the benefits of pressure infiltration of chemicals through the skins of whole fresh fruits and vegetables have been demonstrated, practical difficulties have arisen in identifying effective infiltration techniques, particularly with respect to open calyx fruits. When such fruits, such as Golden Delicious apples, were treated with calcium chloride while immersed in a pressure tank, there was a significant increase in calcium absorption through the calyx end. This caused waterlogging in the core area of the fruit and specifically led to the development of the present system as an alternative treatment procedure.
In the present system, the produce is first subjected to vacuum pressure. While the vacuum pressure is maintained, their surfaces are wetted by a liquid spray, by engagement by wetted yieldable rollers, or by both. The application of the liquid is continued during release of the vacuum pressure. The resulting pressure increase effectively forces the liquid through the pores of the skin surrounding the fruit or vegetable without any significant variations in liquid uptake at the calyx end, if present.